This invention relates generally to means for effecting actuation of electrical switches and in particular to a toggle device, an electrical switch incorporating a toggle device, and a method of loading a toggle device.
In the past, various types of toggle devices were utilized in many different types of electrical switches for relatively moving a pair of contacts with snap-action between making and breaking positions in a circuit. Generally, each of the past toggle devices was provided with an operator or arm pivotally movable for actuating the contacts between make and break positions, and one of a pair of opposite ends of a toggle spring was pivotally engaged with the arm.
In order to obtain effective toggling operation in one such past toggling device, the toggle spring thereof was loaded or adjusted against the toggle arm, normally in a direction generally parallel thereto, and such loading effected only a selected differential between the tripping force and the resetting force of the toggling device. Of course, one of the disadvantageous or undesirable features of this past toggling device was that although the differential between the tripping and resetting forces was adjustably preselected, the magnitudes of the tripping and resetting forces could not be adjusted to preselected values.
In order to predeterminately select the magnitude of the tripping force desired, an additional bias or range spring was utilized to oppose and assist toggling movement of the toggle arm. However, one of the disadvantageous or undesirable features of the past toggle devices employing arrange spring was that the range spring added extra positive gradients to the toggle device thereby to necessitate further increasing the effect of the toggle, i.e. the negative gradient action, to obtain the desired differential between the tripping and resetting forces. This type of past toggle device, as utilized in a thermostat, is illustrated in U.S. Pat. Nos. 3,629,769, 3,648,214 and 3,654,378.
Other past toggle devices were provided with an additional adjustment which adjustably varied stop abutments for controlling the reciprocal movement or stroke of the toggle arm, but one of the disadvantageous or undesirable features of this type of past toggle device was that the distance through which the driving force moved was not constant and/or the direction of the driving force was altered during adjustment.